Complete assignment of 1H and 13C NMR spectra of α‐phenylsulfinyl‐N‐methoxy‐ N‐methylpropionamide and some p‐substituted derivatives

The complete assignment of the ¹H and ¹³C NMR spectra of the diastereomeric pairs of some α‐arylsulfinyl‐substituted N‐methoxy‐N‐methylpropionamides with the substituents methoxy, methyl, chloro, nitro is reported. Copyright © 2008 John Wiley & Sons, Ltd.     

1H and 13C NMR spectral assignments of pyridinium salts linked to a N‐9 or N‐3 adenine moiety

¹H and ¹³ C NMR spectral data of 13 new compounds containing a 4‐(dimethylamino)‐ or 4‐(pyrrolidin‐1‐yl)pyridinium moiety linked to the N‐9 or N‐3 nitrogen atom of an adenine moiety were assigned. 1D and 2D NMR experiments (DEPT, HSQC and HMBC) allowed the unequivocal identification of N‐9 and N‐3 isomers. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and 1H and 13C NMR structural analysis of cis‐ and trans‐2‐imino‐1,3‐ and ‐3,1‐perhydrobenzoxazines and their 3‐ and 1‐N‐methyl derivatives

cis‐ and trans‐2‐imino‐1,3‐ and ‐3,1‐perhydrobenzoxazines and the N‐methyl derivatives of the latter were synthesized from the corresponding cyclic 1,3‐amino alcohol with cyanogen bromide. The configurations of the studied compounds were confirmed by ¹H and ¹³C NMR spectra. All trans‐fused compounds exist in biased chair–chair conformations as expected, whereas the cis‐fused 1,3‐benzoxazines attain exclusively the O‐in conformations. The cis‐fused 3,1‐benzoxazines, especially the 1‐methyl‐substituted derivatives, tend to favor the N‐out form, obviously owing to the favorable axial orientation of this N‐methyl. Copyright © 2003 John Wiley & Sons, Ltd.     

Structural determination of ε‐lactams by 1H and 13C NMR

The thermodynamic products (ε‐lactams) of the degradation of ten different spirocyclic oxaziridines were analyzed by ¹H and ¹³C NMR spectroscopy. The preferred conformations were determined by examining the homonuclear spin–spin coupling constant and the chemical shift effects of the N‐substituent and the alkyl group of the aliphatic ring on ¹H and ¹³C NMR spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

1H, 13C and 15N NMR assignments for N‐ and O‐acylethanolamines,important family of naturally occurring bioactive lipid mediators

The complete ¹H, ¹³C and ¹⁵N NMR signal assignments of some N‐ and O‐acylethanolamines, important family of naturally occurring bioactive lipid mediators, were achieved using one‐dimensional and two‐dimensional experiments (gs‐HMQC and gs‐HMBC). Copyright © 2012 John Wiley & Sons, Ltd.     

1H and 13C spectral assignment of o‐chloroformyl substituted 1,4‐dihydropyridine derivatives

The ¹H and ¹³C NMR spectroscopic data for alkyl 4‐aryl‐6‐chloro‐5‐formyl‐2‐methyl‐1,4‐dihydopyridine‐3‐carboxylates were fully assigned by combination of one‐ and two‐dimensional experiments (DEPT, HMBC, HMQC, COSY, NOE). Copyright © 2002 John Wiley & Sons, Ltd.     

1H and 13C NMR spectral assignments of 2′‐hydroxychalcones

Chalcones are of interest to medicinal chemists because their structures can be easily modified with various functional groups. The syntheses and biological activities of chalcones from natural sources are well known. In this study, 24 2′‐hydroxychalcones bearing methoxy substituents were synthesized, among which five are new. The NMR data for all synthesized chalcones are described for the first time. The complete assignments of the ¹H and ¹³C NMR data can be used for the identification of newly discovered and widely isolated, synthesized chalcones. Copyright © 2013 John Wiley & Sons, Ltd.     

3‐Methylflavones characterization revisited: complete assignment of 1H and 13C NMR data

Ten 3‐methylflavone derivatives were studied. Previously reported NMR data of some derivatives were corrected and/or completed, including the complete assignment of the two known natural derivatives. The complete ¹H and ¹³C NMR assignments were achieved by combination of one‐dimensional and two‐dimensional NMR experiments. Copyright © 2013 John Wiley & Sons, Ltd.     

1H, 13C and 15N NMR investigation of a new,condensed hexahydro‐1,3,5‐triazine

Treatment of 2‐acetyl‐2‐methylcyclopentanone with hydrazine hydrate yielded a new condensed hexahydro‐1,3,5‐triazine (3b), which is the first example of the ketimine‐type trimers. A complete ¹H, ¹³C and ¹⁵N NMR assignment of the compound was achieved. Copyright © 2003 John Wiley & Sons, Ltd.     

1H and 13C NMR spectral assignment of N,N′‐disubstituted thiourea and urea derivatives active against nitric oxide synthase

The ¹H and ¹³C NMR resonances of seventeen N‐alkyl and aryl‐N′‐[3‐hydroxy‐3‐(2‐nitro‐5‐substitutedphenyl)propyl]‐thioureas and ureas ( 1–17 ), and seventeen N‐alkyl or aryl‐N′‐[3‐(2‐amino‐5‐substitutedphenyl)‐3‐hydroxypropyl]‐thioureas and ureas ( 18–34 ), designed as NOS inhibitors, were assigned completely using the concerted application of one‐ and two‐dimensional experiments (DEPT, HSQC and HMBC). NOESY studies confirm the preferred conformation of these compounds. Copyright © 2016 John Wiley & Sons, Ltd.     

Complete assignment of the 1H and 13C NMR spectra of antimicrobial 4‐arylamino‐ 3‐nitrocoumarin derivatives

Herein, we describe the synthesis and complete assignment of the ¹H and ¹³C NMR chemical shifts of a series of antimicrobial 4‐arylamino‐3‐nitrocoumarin derivatives based on a combination of ¹H and ¹³C NMR, ¹H‐¹H‐COSY, NOESY, HSQC and HMBC experiments. Conformational effects upon the chemical shifts of the coumarin moiety arising from the anisotropy of the aryl side group are briefly discussed. This study provides the first complete and fully assigned NMR data for this important group of antimicrobial compounds and bridges the gap existing in the literature with regard to NMR structural data for 4‐arylamino‐3‐nitrocoumarins. Copyright © 2010 John Wiley & Sons, Ltd.     

One‐step synthesis of 6‐acetamido‐3‐(N‐(2‐(dimethylamino) ethyl) sulfamoyl) naphthalene‐1‐yl 7‐acetamido‐4‐hydroxynaphthalene‐2‐sulfonate and its characterization with 1D and 2D NMR techniques

A one‐step method was reported for the synthesis of 6‐acetamido‐3‐(N‐(2‐(dimethylamino) ethyl) sulfamoyl) naphthalene‐1‐yl 7‐acetamido‐4‐hydroxynaphthalene‐2‐sulfonate by treating 7‐acetamido‐4‐hydroxy‐2‐naphthalenesulfonyl chloride with equal moles of N, N‐dimethylethylenediamine in acetonitrile in the presence of K₂CO₃. The chemical structure of the obtained compounds was characterized by MS, FTIR, ¹H NMR, ¹³C NMR, gCOSY, TOCSY, gHSQC, and gHMBC. The chemical shift differences of ¹H and ¹³C being δ 0.04 and 0.2, respectively, were unambiguously differentiated. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of 2‐aryl‐1,3,4‐oxadiazoles by 15N and 13C NMR spectroscopy

¹⁵N NMR chemical shifts of 2‐aryl‐1,3,4‐oxadiazoles were assigned on the basis of the ¹H–¹⁵N HMBC experiment. Chemical shifts of the nitrogen and carbon atoms in the oxadiazole ring correlate with the Hammett σ‐constants of substituents in the aryl ring (r² ≥ 0.966 for N atoms). ¹⁵N NMR data are a suitable and sensitive means for characterizing long‐range electronic substituent effects. Additionally, ¹³C NMR data for these compounds are presented. Copyright © 2003 John Wiley & Sons, Ltd.     

1H and 13C NMR signal assignments of some new N,N′‐diacyl proflavine derivatives

The complete ¹H and ¹³C NMR signal assignments of 23 new N,N′‐diacyl proflavine derivatives were achieved using one‐ and two‐dimensional experiments (DEPT, HMQC and HMBC). Copyright © 2009 John Wiley & Sons, Ltd.     

1H and 13C NMR study of 2‐hydroxyglutaric acid and its lactone

Determination of the level and absolute configuration of 2‐hydroxyglutaric acid in a patient's urine is a method of diagnosing two metabolic diseases. Such a determination can be done with the aid of NMR spectroscopic methods. In this paper the careful interpretation of ¹H and ¹³C NMR spectra of this metabolite and its lactone measured under conditions used in biomedical assays is reported. The ¹H chemical shifts and spin–spin coupling constants were derived using the total lineshape analysis method. Copyright © 2002 John Wiley & Sons, Ltd.     

1H, 13C and 15N NMR chemical shifts of substituted pyrazolo[1,5‐a]pyrimidines

¹H, ¹³C and ¹⁵N NMR chemical shifts of 10 substituted pyrazolo[1,5‐a]pyrimidines were assigned based on DQF ¹H, ¹H COSY, PFG ¹H, ¹³C HMQC and PFG ¹H,X (X = ¹³C and ¹⁵N) HMBC experiments and on literature data. Copyright © 2002 John Wiley & Sons, Ltd.     

Heterocyclic analogs of xanthiones: 5,6‐fused 3‐methyl‐1‐phenylpyrano[2,3‐c]pyrazol‐4(1H) thiones—synthesis and NMR (1H, 13C, 15N) data

Various [5,6]pyrano[2,3‐c]pyrazol‐4(1H)‐thiones were synthesized in high yields by treatment of the corresponding [5,6]pyrano[2,3‐c]pyrazol‐4(1H)‐ones with Lawesson's reagent. Detailed NMR spectroscopic studies were undertaken of the title compounds. Complete and unambiguous assignment of chemical shifts (¹H, ¹³C, ¹⁵N) and coupling constants (¹H,¹H; ¹³C,¹H) was achieved by the combined application of various one‐ and two‐dimensional (1D and 2D) NMR spectroscopic techniques. Unequivocal mapping of most ¹³C,¹H spin coupling constants is accomplished by 2D (δ, J) long‐range INEPT spectra with selective excitation. Copyright © 2010 John Wiley & Sons, Ltd.     

Complete assignment of 1H and 13C NMR data of some flavonol derivatives

Nine flavonol derivatives were studied. Previously reported NMR data of three of these derivatives were corrected. We report complete assignments of the NMR data for six flavonol derivatives not previously studied.     

Theoretical and experimental 1H, 13C and 15N NMR studies of N‐alkylation of substituted tetrazolo[1,5‐a]pyridines

The ¹⁵N as well as ¹H and ¹³C chemical shifts of nine substituted tetrazolopyridines and their corresponding tetrazolopyridinium salts have been determined by using NMR spectroscopy at the natural abundance level of all nuclei in CD₃CN. In this paper, we report, for the first time, the N‐alkylation reaction of electron deficient tetrazolopyridines. The treatment of tetrazolopyridines 5–13 with one equivalent of trialkyloxonium tetrafluoroborate leads to a mixture of two isomers, i.e. N3‐ and N2‐alkyl tetrazolo[1,5‐a]pyridinium salts. It has been observed that the N3‐isomer is always the major isomer, except in the case of the CF₃ substituent, where the two isomers are obtained in the same amount. The quaternary tetrazolopyridinium nitrogen N3 is shielded by around 100 ppm (parts per million) with respect to the parent tetrazolopyridine. Experimental data are interpreted by means of density functional theory (DFT) calculations, including solvent‐induced effects, within the conductor‐like polarizable continuum model (CPCM). Good agreements between theoretical and experimental ¹H, ¹³C and ¹⁵N NMR were found. The combination of multinuclear magnetic resonance spectroscopy with gauge including atomic orbital (GIAO) DFT calculations is a powerful tool in the structural elucidation for both neutral and cationic heterocycles and in the determination of the orientation of N‐alkylation of tetrazolopyridines. Copyright © 2009 John Wiley & Sons, Ltd.     

Unequivocal total assignment of 13C and 1H NMR spectra of some pyrido[1,2‐a]pyrimidine derivatives by 2D‐NMR

We report the total assignments of the ¹³C and ¹H NMR spectra of some 4‐methyl‐2‐oxo‐(2H)‐pyrido[1,2‐a]pyrimidine and 2‐methyl‐4‐oxo‐(4H)‐pyrido[1,2‐a]pyrimidine derivatives. The products were characterized by ¹H and ¹³C NMR and reported data for similar compounds. No comparative data for the two sets of isomeric compounds with respect to ¹³C and ¹H NMR have been reported to date. We made some detailed studies of the 2D NMR spectra of these compounds and observed that assignments made for non‐protonated carbon atoms by us and those reported in the literature for similar compounds need correction. The revised assignments were made on the basis of heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC) techniques. Copyright © 2003 John Wiley & Sons, Ltd.